In this part of the clinical approach to asthma we will discuss the background to asthma. That includes:

• Background
  • Asthma vs COPD
    • Reversibility in asthma
    • Difficulty to manage when asthma is chronic
    • Varying airflow obstruction
  •  Need to prevent remodeling of the lung tissue while managing asthma.
  • Higher prevalence of asthma in affluent countries.
  • Peak age for asthma (3 years of age)
  • Gender in childhood is predominantly boys, however, the gender difference goes away in adults.
  • Asthma by itself is not a fatal disease, however, asthma related deaths can occur due to the underlying inflammation and tissue damage.
  • The basic principle of the management is to control the inflammation - not just the symptoms.
  • Why did the mere use of beta agonists actually increased deaths in the asthma patients? (happened in 1960)
  Risk Factors
  • Atopy (Antigen vs. allergen)
  • Infections
  • Diet
  • Air Pollution
  • Occupational exposure
  Triggers
  • Why does laughing and coughing trigger asthma?
  • Role of the mast cells in triggering asthma.
  • Nerve irritation leading to the asthma.
  • Beta blockers (can be fatal.)
  • Exercise. Why does exercise trigger asthma?
  • Cold air, hyperventilation
  • Food
  • Air pollution
  • Occupational factors
  • Hormones (some women before periods can have attacks of asthma.)
  • Gastroeosphageal reflux
  • Stress. Why will stress cause asthma?
  Pathophysiology of asthma
  • Airway inflammation
  • Airway hyper-responsiveness
  • Epithelial shedding due to irritation and inflammation.
    • Loss of epithelium derived nitric oxide.
    • Protection mechanism disappears leading to nerve exposure and nerve irritation.
    • Thickening of the basement membrane leading to irreversibility/difficulty in management. 
    Airway smooth muscle changes
    • Beta receptor decoupling
    • Hyperplasia and hypertrophy of the airway smooth muscles
    Vascular changes
    • Increased blood vessels.
    • More blood flow.
    • Edema
    • Inflammation
    • Swelling
    • Increased mucus secretion
    Mucus hypersecretion
    • Result of chronic irritation and inflammation
  Diagnosis
  • Pulmonary function tests and the changes
  • Inhaled SABA based testing to confirm asthma.
  • Blood IgE tests
  • Imaging
  • Skin tests
  • Exhaled nitric oxide (NO)